This proposal will be concerned with the chemical, biological and clinical studies on human chorionic gonadotropin and other gonadotropins. Studies on the primary structure of human chorionic gonadotropin will be continued especially on the elucidation of the fine structure of the carbohydrate units. Structural investigations will also be conducted on the disease state hCG from the urine of persons with trophoblastic tumors and from the choriocarcinoma tissue culture. Studies on the monosaccharide and amino acid sequences of PMSG and equine FSH will be undertaken. Structure-activity studies of hCG will be continued with a view to not only delineate the parts of the molecule essential for biological activity, but also to elucidate the molecular mechanism of gonadotropin action. These studies will be corroborated with the conformational analyses of the modified forms of hCG. Biosynthesis of LH or hCG in vitro in the pituitary gland and placenta will be studied by using tissue slices and appropriate sugar nucleotides. The inhibitors of glycosyl transferases will be explored. Attempts will be made to isolate and characterize gonadotropin receptors from pig ovaries. Finally, the work on the development of the pregnancy specific antiserum and of the antifertility vaccine based on the principle of active immunization will be undertaken.